The present invention relates to laminated ballast cores and, more particularly, to a laminated ballast core having two multiple piece, generally L-shaped sections joined to form the core.
Transformers perform numerous electrical functions. When connected as a series choke coil in a lighting circuit, the transformer functions as a ballast to limit the current to which the lamp may be exposed. Industry specifications require that the ballast limit current in the lamp circuit such that if a voltage swing of plus or minus five percent of normal line voltage occurs, the wattage to which the lamp will be exposed is limited to plus or minus twelve percent of rated wattage.
Because of the high production volume of lighting fixtures, it is desirable to cut production costs as much as possible while also producing an electrically efficient light fixture. The ballast is an element in such fixtures so it is equally desirable to produce a low cost and efficient ballast. The most widely accepted design of such ballasts has been an "E I" construction. In such a laminated ballast core arrangement, two generally E shaped lamination sections are punched from a rectangular plate of lamination material, usually cold rolled or transformer silicon steel. The E shaped sections are punched side to side, thereby producing two "I" shaped or finger like sections between the legs of the E shaped sections. A selected portion of the middle leg is removed to form a gap between the E sections aligned adjacent to each other with the I sections aligned and welded as a unit to the top and bottom legs of the E sections. A dual spacing is provided in the assembled core where the I sections were punched from the E sections. More efficient use of the laminate material and better and more consistent electrical characteristics of the laminated cores are desired over this known core configuration.
Accordingly, it is an object of the present invention to provide an improved laminated ballast core construction.